I've been out of the office all day, so not able to respond until now. Have even gotten a couple of emails from peeps wondering why I haven't chimed in yet, so I picked Scan's mail as a basis for reply because it most efficiently summarizes my own boiled down philosophy, with one caveat. I agree with the early posts from this morning's onset of the thread, and the information presented so far is accurate and consistent with the committee's intent, methinks. A few clarifications and enhancements:
I have rep'd AFSA on the 14 since '99 or 2000, so don't have personal knowledge of what happened in the '93 cycle. However (to drop a few names), I have had the chance over the years to talk with some people who were either on the committee or have personal knowledge of how it came down, such as former NFPA staff liaison David Hague, committee members Maurice Pilette, Jeffry Shapiro and Chet Schirmer. As Jim previously stated, the 65psi rule in earlier editions was based on fixed bore nozzles and 65psi was enough to allow friction loss in the hose and still give a good pattern and throw distance from a straight stream tip. But fire departments were seizing on the still-relatively-new Elkhart Select-A-Flow nozzles and they were rated for 100psi at the tip. So the thinking was that if you calculated friction loss at 250gpm through 1-3/4" and 2-1/2" hose, you'd need at least 125psi and perhaps 150. If you split the flow, 125gpm through each of 2 1-1/2" attack lines will cause up to 50psi of loss as well, so the idea was originally to bump it to 150. And there was much rejoicing by the pump people ... But it became apparent that such a radical upgrade would get NITMAM'd out of the room at the code hearing so the TC arrived at 100psi as a good compromise. Not terribly scientific but strategically sound and it wasn't challenged. But that pressure may or may not be adequate for all tactical op's and as others have already said, you need to correspond with the fire department to be sure of what they need or want. So why didn't we change the standard to mandate that it be purely performance based? We fielded two proposals two cycles ago that would have made higher pressure and/or FD specification of pressure the norm, but both were voted down and the annex language added instead. Why? Because the thinking was that many fire departments don't have the knowledge or expertise to specify engineering criteria and that's likely true. Some FPO's don't even know what their trucks are carrying for equipment. Elkhart now makes selectable nozzles in 100psi (Select-A-Flow) and 75psi (Phantom) classes. They also make the Chief, which is a 50psi tip. Task force makes a tip that is selectable flow AND pressure in 50-75-100 psi settings, so it's incredibly versatile and will function across a wide range of water supply. But it costs a lot more than Brands X, Y and Z. Akron Brass makes a tip that will handle up to 500psi, which feeds into the HP trend we're seeing across the board (think mist). Clark County FD in Las Vegas is experimenting with standpipe working pressures up to 400psi at their training center, if I'm not mistaken. It should be performance based yes, but the EOR or designer of record should be prepared to design per the prescription if that's the fall back. Should it be higher? Yes ... maybe ... <shrug of shoulders>. Anyway and bottom line, instead of prescribing higher pressures or a go-to with the fire department, we added A7.8 and I will take credit for writing at least half of it myself. I'm not happy with the table as it's confusing and poorly worded; the most common high-rise tactic as best as I can tell is to drop a 6-8' section of 2-1/2" rubber hose on the deck and connect a 2-1/2" x 1-1/2" x 1-1/2" gated wye, and then run one or two 1-1/2" attack lines flowing 125-175gpm. This configuration will likely impart at least 40psi of friction loss up to 55psi, depending on variables. So for a 75psi tip you'd want at least 115-120psi at the valve, or more. For a 100psi tip it could easily be higher. Another thing to consider in high-rise buildings (that was mentioned on this thread) is pressure reducing valves. I personally would like to see it mandatory that any such appliance be field adjustable at the POC, ideally in both flow and no-flow conditions. But that would essentially prescribe either an Elkhart or Giacommini and we can't do that. But if we could, we could specify that systems be capable of high pressures and then set the valves down to a lower one. In San Diego, our firefighters carry adjusting rods for those valves in their hose packs and we do have a policy here that mandates the use of one or the other product. Contrast that with City of San Francisco, where trucks carry three sets of tips so that fire fighters can effectively use standpipes from three different eras. As mentioned previously the One Meridian fire was NOT an example of PRV failure - they worked perfectly. The fire went out of control because of a lack of sprinklers and a complete meltdown by building security, but when the FD finally arrived and tried to wet it down they were using 100psi tips on valves set for 65psi max and they only had 15 usable PSI at point of attack. It is CRITICAL that the standpipe system be capable of providing pressure across a usable range for firefighters responding from a particular agency and we (industry) have to remember that sometimes decisions are made by purchasing agents who outfit hose packs with a particular nozzle and that's that for the next however many years. Then, the question becomes, will the next PA buy new equipment with the same performance parameters? Whenever I do a seminar or when I'm pontificating (as now), I always say that standpipes should be performance based as a first option. If a Fire Department needs/wants pressures in excess of the NFPA 14 prescriptives, they should establish a policy or engineering bulletin and put it out there. If an FD expresses a preference for this pressure or that, industry should conform unconditionally and without question; it's their system, not ours or the building owner's. But keep in mind too that there are still a few FD's out there using straight streams that allow/require lower pressures: does anyone know if Tampa Bay is still using 65psi? The foregoing is my opinion only and does not necessarily represent the opinion or intent of the NFPA 14 Technical Committee on Standpipe and Hose Systems. Steve Leyton Protection Design & Consulting San Diego, CA -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Steven Scandaliato Sent: Wednesday, February 19, 2014 11:01 AM To: [email protected] Subject: RE: 100 PSI requirement at top of Standpipe Bingo....the title for NFPA 14 should be changed to "Standard for the Installation of Standpipe Systems"....Chapter 1 - Call the guy who is going to fight the fire and ask him what he wants". Chapter 2 - "don't argue with the guy who is fighting the fire; rather give him what he is asking for". Chapter 3 - Do chapter 1 and chapter 2 BEFORE you bid the job. Peace, Steven Scandaliato, SET CFPS 520.971.2322 Cell Skype: steven.scandaliato _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
